import re
a='''
<link rel="dns-prefetch" href="//static.360buyimg.com"/> 
<link rel="dns-prefetch" href="//misc.360buyimg.com"/> 
<link rel="dns-prefetch" href="//img10.360buyimg.com"/>
<link rel="dns-prefetch" href="//img11.360buyimg.com"/> 
<link rel="dns-prefetch" href="//img12.360buyimg.com"/>
<link rel="dns-prefetch" href="//img13.360buyimg.com"/>
<link rel="dns-prefetch" href="//img14.360buyimg.com"/>
<link rel="dns-prefetch" href="//img20.360buyimg.com"/>
'''
#要求同学们用正则来去匹配所有带有img字段
m=re.findall('href="(//.*?img.*?)"/>',a,re.S)
for i in m:
    print(i)
